1. Field of the Invention
The present invention relates to an organic electro-luminescent display and method for fabricating the same and, more particularly, to an organic electro-luminescent display with micro-lenses and method for fabricating the same.
2. Description of the Related Art
Recently, with the development and wide application of electronic products, such as mobile phones, PDA, and notebook computers, there has been increasing demand for flat display elements which consume less electric power and occupy less space. Among flat panel displays, organic light-emitting diodes (OLEDs) or namely organic electroluminescent devices are self-emitting, and highly luminous, with wider viewing angle, faster response, and a simple fabrication process, making them the industry display of choice.
In organic electroluminescence, electrons are injected from a cathode layer and holes from an anode layer, and the applied electric field induces a potential difference, such that the electrons and holes move and centralize in a thin light-emitting layer, resulting in recombination and light emission. Internal quantum efficiency of an OLED is the internal efficiency of converting electricity to light. After exciting the organic moleculars, a quarter of the excited electrons assume a singlet-state asymmetric spin configuration, releasing energy in the form of fluorescence. The other three-quarters assume triplet-state symmetric spin configuration, and release energy in the form of phosphorescence. The triplet state excited electrons also release energy in the form of phosphorescence in organometallic compounds. Therefore, OLED internal quantum efficiency depends on the excitation mechanism, and on the fluorescence or phosphorescence of luminescent material chosen. Currently, the higher internal quantum efficiency is to use the phosphorescent materials instead of fluorescent materials.
The external quantum efficiency of an OLED is the ratio of light output from the device to that from the organic layer inside the device. In a typical OLED, not all light from the organic layer can pass through the device, with more than 40% of OLED light lost to surface plasmon resonance. In addition, the organic material and the glass substrate have a higher refraction index than air, so some light is limited in the device due to total reflection, some scattering outward from the device side. Around 80% of light is dissipated in the device, making conventional OLED external quantum efficiency below 20%. If the unused device light can be recovered, the OLED external quantum efficiency improves.
U.S. publication application 2003/0020399 discloses an organic electro-luminescent display 10, referring to FIG. 1. The organic electro-luminescent display 10 has a substrate 20, and a plurality of organic electro-luminescent diodes 30 is formed on the inner side of the substrate 20 and a plurality of micro-lenses 40 is formed on the outer side of the substrate 20. The emission light of the organic electro-luminescent diodes 30 can be introduced to the surrounding (or namely environment) via the micro-lenses 40, thereby enhancing the external quantum efficiency of the organic electro-luminescent display 10. Referring to FIG. 2, the conventional organic electro-luminescent display with micro-lenses 40, however, results in problems of image blur.
Referring to FIG. 3a, an observer 50 receives the emission light from the sub-pixel 32 passing through the micro-lenses 40 and would misunderstand the sub-pixel 32 located on the location 33 via line of vision. Therefore, the observer 50 would overlap the emission light of the sub-pixels 32 and 34 in different pixels 60, resulting in problems of image blur, referring to FIG. 3b. 
Accordingly, a new structure capable of improving the problems of image blur of organic electro-luminescent devices and enhancing the external quantum efficiency in organic electro-luminescent devices.